A 3D in vitro organotypic model of the human respiratory epithelium was cultured at the Air-Liquid Interface (ALI) and exposed to cigarette smoke and e-cigarette aerosol, generated by using a VITROCELL® VC1 smoking machine under Health Canada Intense and CORESTA conditions.The results are shown in tissue viability (MTT), barrier integrity (TEER), Barrier function, tissue secretion of the pro-inflammatory cytokines (IL-6 and IL-8). The presence of 8-isoprostane is used as an indicator of oxidative stress and antioxidant deficiency. Additionally the tissue morphology was assessed by H&E staining and immunofluorescent staining was conducted for specific markers.

Introduction
In 2015,Public Health England characterised e-cigarettes as being around 95% less harmful than smoking. In2016, the UK Royal College of Physicians concluded that the long-term health risks associated with e-cigarettes are unlikely to exceed 5% of those associated with smoked tobacco products and may be substantially less. However, some recent data has reported that e-cigarette aerosol can potentially produce reactive oxygen species which may give rise to inflammation, DNA damage and reduced cell viability. To investigate these claims, we studied the effect of two different e-liquid aerosols on EpiAirwayTM 3D tissue and a variety of biological endpoints.